The present invention relates to a lens array used in an image forming apparatus, a reading apparatus or the like. The present invention also relates to an exposure device using the lens array, and an LED head using the exposure device. The present invention also relates to an image forming apparatus and a reading apparatus using the lens array.
There are known an image forming apparatus having an LED head in which a plurality of LEDs (light emitting diodes) are arranged in an array, and a reading apparatus (such as a scanner or a facsimile machine) having a light receiving portion in which a plurality of light receiving elements are arranged in an array. Such an apparatus uses a rod lens array as an optical system that forms an erected image of an object at 1:1 magnification in the form of a line. In this regard, it is proposed to provide a light shielding member between adjacent lens elements of the rod lens array (see, for example, Japanese Laid-Open Patent Publication No. 2005-122041).
Further, there is known a lens array including a plurality of microlenses arranged in an array, which forms an elected image of an object at a magnification of 1:1 in the form of a line. The lens array with the microlenses can be efficiently formed with high form accuracy using plastic injection molding, and therefore a high resolution can be obtained.
However, when the conventional lens array is used, a phenomenon (called a flare) where a light from an object reaches an imaging plane without being collected may occur. In such a case, a sufficient resolution can not be obtained.